If the soundcard does not support the requested rate, the sound is
converted at software level.

Recording from left or right channel

It may be sometimes interesting to record (in mono) from left or right
channel of a stereo sound.

For example, the Edirol UA-25 audio
device has two mono microphones inputs, which are combined into a
stereo (right/left) sound during recording. Whenever you record your
voice using one mono microphone, the output is stereo, with a blanck
channel being degraded by noise.

Some software may be able to transform the stereo sound into a mono
sound, mixing the recorded voice (first channel) with noise (second
channel), thus degrading sound quality.